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Currently, the cascades optimizer of databend is implemented in a recursive fashion instead of top-down, which is easy to maintain but can not really enumerate all the search space.
Besides, we can…
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**manage rule by bitmap**
my gporca article: (https://blog.csdn.net/dusx1981/article/details/124553274)
Regarding determining the rules used by Operator, GPORCA's solution is to use bitmaps to m…
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## Description
## Bug Report
Please answer these questions before submitting your issue. Thanks!
### 1. Minimal reproduce step (Required)
`drop table if exists t1, t2;`
`create table t1(a bi…
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**Summary**
Description for this feature.
chain.test
```
statement query T
explain select * from t, t1, t2 where t.a = t1.a and t1.a = t2.a;
```
```
2022-10-19T06:11:22.052437Z ERROR d…
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There are some discussions about datafusion's optimizer framework in #440 and #1972. And I tried to build a framework based datafusion's expression system with the following features:
1. Includes a…
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Original Author: @shelby3
Original URL: https://github.com/keean/zenscript/issues/35#issue-243345358
Original Date: July 17, 2017
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![](https://upload.wikimedia.org/wik…
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# Background
Problems with existing optimizers:
1. The degree of cohesion is not high enough, and there are certain limitations on scalability.
2. Forming from the bottom to the top at one time, …
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Now, Doris's query optimizer is inherited from Apache Impala. Current optimizer is based on rule and not a cost based optimizer, as a result for some query it can't get optimal execution plan. Besides…